Driven piles are used to support power transmission lines and other structures that impose vertical and horizontal loads. Various configurations of driven piles are known in the art. There is a configuration of drilled-in pile comprising a cylindrical shaft made of metal, with a tip connected by butt welding to the end of the cylindrical shaft, and with the cylindrical shaft covered with anticorrosion coating (patent RU No. 123795, IPC E02D5/22).
There is a configuration of piles with increased reliability against the effects of frost heaving of the soil on the pile, comprising a cast-in-situ reinforced concrete shaft, concreted in the hole, with a metal casing in the area of influence of frost soil heaving, whose cross-section is less than the cross section of the hole. The casing has an anti-heaving coating on the outer surface. The casing is not attached to the fixture of the pile, and the space between the casing and the hole walls is filled with hydrophobic soil (patent RU No. 118324, IPC E02D5/60).
The disadvantage of the above installations is insufficient bearing capacity against horizontal loads and inability to exclude the impact of frost heaving.
There is a configuration of driven pile comprising a shaft with a longitudinal hole in it, a pointed tip, and a device that increases the bearing capacity of the pile. The bottom of the shaft has a recess with a cylindrical surface, an elastic coating with the tools fastening its upper and lower ends, which covers the cylindrical surface of the recess; a space between the elastic coating and the cylindrical surface of the recess; protective housing extendible in radial axis with its fastening tools on the shaft, and covering the elastic coating. The shaft has a radial hole connecting the longitudinal hole with the above cavity, transformed in a supporting skirt after immersing the pile to a predetermined depth, filling the cavity with hardening mortar through the holes in the shaft and mortar hardening (patent RU No. 85171, IPC E02D5/48). However, fabrication of such a pile structure requires much labor for manufacturing and as a consequence an increased time of the work.
There is a configuration of driven pile comprising a shaft with a longitudinal through hole, a pointed tip, a device increasing the bearing capacity of the pile, positioned between the shaft and the tip in a form of an insert with a longitudinal hole; attached to them, having the elastic coating with the tools to fasten its upper and lower ends, and covering the cylindrical surface of the insert. The cavity between the elastic coating and the cylindrical surface of the insert, a housing extendible in radial axis with its fastening tools on the shaft, covering the elastic coating. The shaft has a radial hole connecting the longitudinal hole with the cavity, transformed in a supporting skirt after immersing the pile to a predetermined depth, filling the cavity with hardening mortar through the holes in the shaft and mortar hardening. The pile shaft may be prismatic or cylindrical, and the tip may be conical, pyramidal or wedge-shaped. The pile has high bearing capacity with reduced power of immersion into the soil (patent RU No. 2386749, IPC E02D5/48). However, this pile design has low bearing capacity when subjected to horizontal forces on the pile, and under the action of wind loads on poles and wires.
Another configuration of piles, in the construction of the pile foundations for resisting major vertical and horizontal loads, includes combined vertical and inclined shafts, with reinforcement cages that increase the stability of the vertical piles by braces and anchors of augercast piles (patent RU No. 2303103, IPC E02D5/46). The disadvantage of this configuration is difficulty and complexity of implementation of this installation, the inability to eliminate the impact of frost heaving forces, and the high cost of the work.
There is a technology of erection of foundations named “pile in pipe” (G. Ya. Bulatov, A. Yu. Kostyukova, Civil Engineering Magazine. 2008. No. 1, p. 33-37). This technology consists in the following: after immersing a pipe pile, soft ground is being removed from its cavity, soil plug surface is being leveled, soil plug is being compacted, then a layer of drainage material with seal is being put, after that a foundation pile is being installed to transmit the load from the pilework to the soil plug. However, this design does not have high bearing capability under the action of horizontal forces on the pile.
There is a method of constructing a pile foundation (ref. to Canadian patent No. 2540185, published on 31 May 2005, IPC E02D27/12), according to which at least one metal pile is inserted via a through hole, then it is axially fixed in structure, comprises a bar and at least one lower primary head in contact with the ground; the transverse dimensions of the head are greater than those of the hole. The disadvantage of this invention is an insufficient bearing capacity against horizontal loads
It would be desirable, therefore, to develop new configurations for driven piles that are capable supporting horizontal and vertical loads in soils subject to frost heaving, while being more economical in materials and installation costs.